JP2006-015853 A, published by the Japan Patent Office in 2006, proposes a rotary steering damper for suppressing unintended yaw or yaw oscillation of a front wheel of a motor (cycle while running.
The steering damper comprises two oil chambers delimited by a vane serving as a movable partitioning member in a housing thereof. The vane has equal pressure receiving areas on which hydraulic pressure in the respective oil chambers is received. The two oil clambers are arranged to communicate with each other via a passage provided outside the housing and equipped with a damping valve.
The housing is fixed to handlebars of the motor cycle whereas the vane is fixed to a vehicle body of the motor cycle. When the handlebars are steered, the vane oscillates in the housing and working oil flows in the passage between the two oil chambers delimited by the vane i.e., from a shrinking oil chamber to an expanding oil chamber, and the damping valve imposes a drag on the flow of working oil, thereby generating a damping force.
According to the prior art steering damper, unintended yaw or yaw oscillation of the front wheel and handlebars due to shimmy or kickback can be suppressed by properly setting a cracking pressure of the damping valve.